Year % of adults 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 0 2011 2.5 2012 2.5 2013 2.4 2014 3.5 2015 5.1 2016 10.9 2017 11.2 2018 14.5 2019 19.8